Decoding Accuracy in Supplementary Motor Cortex Correlates with Perceptual Sensitivity to Tactile Roughness

Area of Science:

• Neuroscience
• Sensory Perception
• Human Brain Imaging

Background:

• Tactile roughness perception exhibits significant individual variability.
• Neural mechanisms underlying these individual differences in tactile sensitivity are not well understood.
• Previous studies have explored tactile roughness perception but not its link to individual differences.

Purpose of the Study:

• To investigate human brain activation patterns related to individual differences in tactile roughness discrimination.
• To identify brain regions where neural activity patterns correlate with behavioral sensitivity to surface texture roughness.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to measure brain activity.
• Whole-brain searchlight multi-voxel pattern analysis (MVPA) was used to decode roughness information.
• Behavioral sensitivity was assessed using the just-noticeable difference (JND) and correlated with neural decoding accuracy.

Main Results:

• Four brain regions, including the supplementary motor area (SMA), contralateral postcentral gyrus (S1), and superior temporal pole (STP), showed significant roughness information decoding.
• Only the SMA demonstrated a significant correlation between neuronal decoding accuracy and individual JND.
• Higher decoding accuracy in the SMA was associated with better roughness discrimination ability (smaller JND).

Conclusions:

• Multivariate voxel response patterns in the SMA encode individual perceptual sensitivity to tactile roughness.
• Distinct neural representations in the SMA may underlie enhanced tactile roughness perception.
• The SMA plays a crucial role in mediating individual differences in tactile roughness sensitivity.